This invention relates to quick-acting electric cigar lighters, and more particularly to lighters of this type, which utilize a bimetallic disk in the heating element circuit to control the energization of the element.
The invention involves improvements in the fast-acting electric cigar lighter described and claimed in U.S. Pat. No. 3,760,150 dated Sept. 18, 1973 and issued to Lawrence E. Fenn and Charles R. Sperry.
The quick-acting electric cigar lighter of this identified patent is believed to constitute the closest prior art to the present invention.
In the electric cigar lighter of the patent, an electric heating element that is carried in a contact cup, is mounted at the inner end of a removable igniting unit plug stored in the socket of a holder device. Such socket has contact members which provide for the energization of the heating element. The control of the circuit, involving a mechanical make-and-break arrangement, is effected by flexing of the bimetallic disk as it becomes heated. The condition of the disk when cool is such that peripheral portions thereof can be engaged by the heating element cup at the time that the igniting unit plug is depressed or forced inward. Also, the bimetallic disk, in effect, constitutes a large wall of a temporarily-formed chamber or enclosure containing the heating element, this occurring when the plug is depressed. In consequence, heat from the enerigized coil is transferred very quickly to the bimetallic disk, and as it flexes the peripheral portions thereof snap away from the circuit closing edge of the heating element cup, effectively opening the circuit through the element prior to excessive heating of the latter. The normal rating of the heating element is not sufficient to enable it to withstand for any considerable length of time the current which flows at the time that the igniting unit plug is held depressed. However, the operation of the bimetalic disk can be depended on to prevent overheating and burn-out of the heating element. In this patented fast-acting lighter, the possibility existed that pitting and deterioration of the contacts represented by the bimetallic disk and the cooperate edge of the heating element cup could occur. Also, there existed the possibility that extensive pressures, which might be applied to the igniting unit plug, would cause an undesirable deformation of the bimetallic disk, impairing its proper functioning and conceivably shortening the useful life of the cigar lighter. In addition, under circumstances of extended operation, the tendency existed for the headed joint on which the bimetallic disk depended for its support to fail, or for the disk to crack due to an excessive member of actuations beyond that normally encountered in what was considered to be a useful life.
While the above conditions did not of necessity render the fast-acting cigar lighter of the patent unsuitable for manufacture and sale, it was considered, as with numerous other manufactured products, that improvements could be realized, enhancing still further the desirable features of the lighter.
The conditions described above have been largely obviated by the present invention, which has for one objective the provision of an improved fast-acting electric cigar lighter of the kind described, wherein a greatly extended life of the electric contact means is had.
Another object of the invention is to provide an improved fast-acting electric cigar lighter as above characterized, wherein increased reliability is had in the functioning of the bimetallic disk-like member.
Yet another object of the invention is to provide an improved electric cigar lighter in accordance with the foregoing, wherein there is obviated the likelihood of over-stressing of the bimetallic disk member.
A feature of the invention resides in the provision of an improved fast-acting electric cigar lighter as above set forth, which is especially simple in its construction and economical to fabricate.
Another feature of the invention resides in the provision of an improved electric cigar lighter as characterized, which lends itself to simple, well-known and tested fabricating procedures which make possible mass production without involving costly and complicated machinery and equipment.
Still other features and advantages will hereinafter appear.
In accomplishing the foregoing objects, the invention provides a cigar lighter which utilizes, for the control of the circuitry, an electrical contact between edge portions of the heating element cup that is carried by the igniting unit plug, and a face of the bimetallic disk that snaps to open the circuit. On the two contacting surfaces, different metal are provided which considerably extend the useful life and minimize pitting and deterioration. One of said metals is aluminum, which is preferably provided on the edge of the heating element cup. Cooperating with the aluminum is a facing of copper on the bimetallic disk, and such facing can be of silver instead of copper, with equally good results. The aluminum has the effect of preventing pitting and deterioration when utilized with copper or silver, for example, as the cooperable companion metal.
At the center of the bimetallic disk an offset portion is provided, having reverse bends. The mounting stud has a head which is welded to the offset portion of the disk, and by virtue of the offset bends there are minimized the stresses that occur as the disk responds to heating and cooling, with the result that there is less likelihood of cracking of the disk or failure of the weld.
The bimetallic disk is carried in a mounting block constituted of ceramic or other suitable heat-resistent insulating material. The said block is recessed to receive the bimetallic disk, and has lands at opposite edges of the disk, which are engageable with edge portions of the heating element cup at the time that the igniting unit plug is depressed. Such engagement constitutes a positive stop, and prevents the imposing of excessive stresses on the disk, which would otherwise cause deformation and malfunctioning of the same.